WASHINGTON – An internal District of Columbia police report on the response to the Washington Navy Yard shooting says officers were hindered because they couldn't access live surveillance-camera footage of the shooter.

Military contractor Aaron Alexis killed 12 civilian workers at the Navy Yard's Building 197 in September 2013 before he was fatally shot by police. The Metropolitan Police Department released its 83-page After Action Report on the shooting Friday.

The report says the contract security guard who was monitoring the surveillance videos locked the door to the control room and didn't contact law enforcement. That prevented police from tracking Alexis' movements in real time or ruling out reports of a second shooter.

The report also said Metropolitan Police Department officers were delayed in getting to the scene because some Navy Yard employees called an internal emergency communications number instead of 911 and because officers couldn't get through locked gates when they arrived. That's because the base personnel working at the entrances had followed emergency protocol to lock the gates and respond to the shooting, the report said.

Equipment challenges were also detailed by the report, and the department wrote it is addressing those.

Once officers entered the building, a blaring fire alarm pulled by an evacuating worker or security officer was an "ongoing distraction" and made it difficult to determine where shots were being fired from and hear radio communications, the report said. The police department says it is in the process of getting all of its members earpieces, which will allow officers to better hear communications in loud environments. The report said one officer also believes his radio, which was not attached to an earpiece, may have given away his location as he chased after Alexis, a situation earpieces would prevent.

Police are also obtaining additional weapons. Many years ago, police departments across the country began to acquire semi-automatic rifles to respond in situations where they might be out-gunned by suspects, the report said. But maneuvering in the narrow hallways of Building 197 while armed with a long rifle was a challenge, the report said. The department wrote it is now getting shorter-barrel rifles and including close-quarter maneuvers in training.

The report also stressed the importance of having neighboring law-enforcement agencies conduct collaborative training exercises as well as conducting exercises in many different locations including schools, hotels, hospitals and also military bases. Military bases have often been excluded from training, the report said, even after the shooting at Fort Hood in 2009 where a gunman killed 13 people.

"Police departments may hold the mistaken belief that the personnel working within gated military installations in the United States, such as the Navy Yard, are heavily armed and capable of defending against threats. The truth, however, is that the majority of the individuals working on military bases are not armed," the report said.

Before the shooting, training between the city's police force and their counterparts at the Navy Yard was "minimal," the report said.